I have Logitech 2.1 and Klipsch Promedia sets. According to my power meter, the Logiech consumes 4W when idling while the Promedias consume 1W at most.

Hmm, I wouldn't have guessed that, I would have assumed that they would have much better quiescent current control. But then again, if you're driving it from the wall, then 1W/115V = ~8.5mA of quiescent current, which isn't too bad. Of course, I'm used to trying to keep the quiescent current below 100ľA, so even 8mA seems like a lot to me.

Edit: Come to think of it, that 8mA probably is mostly the LED, I'm also used to working with 13.5Vdc (automotive).